How does designing custom android DPC app relate to Android management API?

There are two distinct ways of managing Android devices:

The new way: the Android Management API. It is the way recommended by Google and it's significantly simpler than the old way, you don't need to call other APIs or to create a custom DPC. If your use case is not addressed by this API you can send feedback to Google so they can add the missing features.

The old way (no longer available for new deployments as of 2019-12-20): using custom DPC. For that you need to:

• create a custom DPC,
• register your custom DPC with Google by joining the EMM Community (this is how you get the afw#DPC_NAME),
• use the Google Play EMM API to install apps.

In the documentation you - the developer using these APIs - are referred as "the EMM". "EMM server" refers to the server that you own and that calls these API, and "EMM console" refers to the UI console that you expose to your IT admins, if any.